It's the same in english. We have a word for one, which we can write, or we can write the arabic numeral 1. Either one is fine. In english writing out the word is considered more formal, but in Japanese it seems to matter less.

For example, for graduation ceremony at the school I work there is a big sign that says 平成１７年度関ヶ原中学校卒業式

The date is typically written in Arabic numerals. Unless it is on an official or a we-want-it-to-look-really-cool document (a certificate or a diploma or something)》hen it's often in kanji.

When counting, I'd say it's about half and half. You might see 2人 as often as you see 二人.

On menus, or signs advertising prices, I'd say it's more often in kanji (with 'Arabic' zeros). Often you might see a tall flag outside a shop that says something is on sale for 五〇〇円. I'd say a lot of menus write this way as well.

Time is usually in Arabic numerals. 11時23分

Addresses on apartment doors are usually Arabic, I would say. I can't really say for sure about houses (and I bet most house don't even HAVE numbers on them like most American homes), but I would bet they are often Arabic--for readability. HOWEVER, when addressing a letter or postcard, it's often kanji (especially if you are written vertically)--and if you want it to look formal/official, it's in kanji.

Any others I may have missed? ^^; I'd imagine so... numbers are used so often in daily life...

Edit: Ha, cool. Those two posts weren't there when I saw this thread. (: Rule for writing numbers in ENGLISH: If it's ten or below, written is preferred in essays, articles, etc. Otherwise, either is fine. (That's what I was told.)

Last edited by Kates on Mon 09.26.2005 8:52 pm, edited 1 time in total.